For new wireless installations, the greatest cost savings occur by avoiding the cost of installing and configuring wire (and conduit) connections. Other considerations for new installations include the following:
Adapt to changes in walls, pipes, and other obstructions that continue to change during construction.
Save additional time and labor because the wireless mesh network is self-configuring and self-correcting.
Communicate with any controller via a wireless connection.
R ep l a c i n g O l d e r N et w o r k s
For retrofit projects, the cost savings vary. Replacement costs could be substantially higher than for new installations, especially in situations where there are:
Older building automation systems containing network cable that may be incompatible or degraded and need to be replaced to
upgrade the system
Networks needing additions and changes that were not considered in the original design
Facilities that need pneumatic controllers converted to direct digital control (DDC) technology
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Historic buildings or buildings with interiors that cannot be disturbed or penetrated
Areas that are hazardous or extremely difficult to access, such as buildings with asbestos covering heating ducts or with clean rooms.
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Appendix A
F req u e n t l y A s k e d Q u es t i o n s A b o u t W i r el es s C o n t ro l s a n d D o ’ s a n d
D o n ’ t s
This chapter provides answers to frequently asked questions about Wireless Controls. Also, included is a brief ‘Do’s and Don’ts’ list in order to avoid overloading or slowing down a wireless system.
Questions and Answers about Wireless Controls
Do’s and Don’ts of Wireless
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Q u es t i o n s an d A n s w er s ab o u t W i r el es s C o n t r o l s
Q: What are the main advantages of wireless controls?
A: Wireless controls reduce installation costs and permit controls to be installed in areas that would otherwise be difficult to wire. The cost of running wire is often the most expensive component of a controls
installation, especially in large cities where labor costs are high and electrical codes require conduit.
Q: What obstacles are still standing in the way of a more comprehensive acceptance of wireless controls?
A: As with any new technology, the adoption rate increases as the technology is proven. A customer wants to know that wireless controls will be reliable, secure and responsive. There needs to be good methods to plan a wireless network in a building, with an understanding of how physical obstacles and building materials affect wireless networks.
With this environmental knowledge, a solid wireless network can be put together by design, rather than trial and error. The technology has now reached a maturity level where these goals can be met at an
attractive cost point for a wide range of applications.
Appendix A: Frequently Asked Questions About Wireless Controls and Do’s and Don’t s
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Q: Although an argument can be made for wireless controls for just about any facility, which building types are the most ideal applications for the technology?
A: There are four types of buildings where a wireless solution is particularly attractive — city buildings, clean rooms, historical
buildings, and difficult-to-wire and remote buildings. In a city, labor costs are especially high and frequently electrical codes require all cables to be run in conduit. Clean rooms need to maintain precise
climate and pressure conditions, so any penetration into the production area decreases its performance. With a historic building, it is important that the historical integrity of the structure is maintained. This means, for example, that wires cannot always be run in a straight path. So, wiring a network to the next room may mean running 1000 feet of cable versus a 10 foot wireless path. Finally, trenching a network cable to a remote building or the penetration of brick, glass, or cement walls may be difficult and expensive.
Q: How should building infrastructures ideally be set up in order to accommodate the greatest adoption of wireless control technologies in the future?
A: One of the major advantages of wireless mesh technology is that an infrastructure does not have to be in place to utilize it. Each wireless mesh node contributes toward building a strong wireless network. A wireless mesh differs from wireless Ethernet, which is a point-to-multipoint network that relies on the strategic placement of access points. In the wireless mesh model, each node has multiple connection paths and knows about all its nearest neighbors. As a result, daisy chain wiring becomes a thing of the past. If one node is disconnected or the current node is blocked, the network heals itself by simply finding its next nearest neighbors and reconnecting messages via the best connection point. Since a wireless mesh does not require an
infrastructure to be created, the total cost savings over wired networks is more easily realized.
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Q: What are the latest technological advantages in wireless controls?
A: The IEEE 802.15.4 wireless standard offers a much better wireless solution for controls over WI-FI and Bluetooth. The wireless mesh networks are self-forming and they do not require an infrastructure or access points and routers, although repeaters may be used. An IEEE 802.15.4 wireless mesh network is secure with optional built-in
encryption and is reliable, since it is self-healing.
Q: Have codes and standards been developing enough to keep up with the latest wireless technologies? Have any new standards recently been passed or are seriously being considered?
A: Zigbee is an emerging wireless standard that is based on the IEEE 802.15.4 wireless standard.
Q: How do you envision the world of wireless controls, 10 and 20 years down the line?
A: With time, buildings will have an ever-increasing proportion of wireless to wired controls in them. Just as an office has a combination of wireless hotspots and wired offices for Ethernet connectivity, there may also be some level of wired controls networks within a facility.
Wireless controls will become common and will include peripheral devices, such as sensors (occupancy, door contacts, intrusion point, temperature, and so on).
Open protocols, such as ASHRAE’s BACnet will adopt a wireless standard as an optional field bus within the standard. With wireless communications standardized for controls it will be possible for
products from multiple vendors to share a common wireless mesh network while interoperating with each other.
Between the reduced installation costs of wireless mesh control
networks and the freedom of choice offered by open protocols, building owners are looking at a future where they can provide safe,
comfortable, and efficient indoor environments with the minimal effort and expense.
Appendix A: Frequently Asked Questions About Wireless Controls and Do’s and Don’t s
Wireless Mesh Network Concepts and Best Practices Guide 57
D o ’ s a n d D o n ’ t s o f W i r el es s
The Wireless network is not as robust as a wired system. Typically a wireless network is approximately 1/3 as fast as an equivalent wired network. The Infinet wireless network treats data exchange (import/
export) differently than a wired configuration. All data exchange is done as a guaranteed delivery point to point communication similar to a BACnet Change of Value (COV) data exchange. Precautions should be taken in programming and configuring the wireless system, to avoid data bottlenecks and network overload.
Do: When you have completed using the Wireless Maintenance Tool, shut it down to avoid overloading the system with unneeded traffic.
Do: When configuring inputs, insure that the threshold is set appropriately.
Don’t: Do not leave ListViews, with several live values running, for extended periods of time. This creates unnecessary traffic that can overload the entire wireless system.
Don’t: When using graphics to poll data from the wireless network controllers, minimize the number of points in the graphic. Do not create a large graphic polling many points. Instead make several smaller graphics with fewer points so as to not overload the network.
Note: When setting the polling rate for graphics, in the Cyberstation Workstation Preferences tab, you may want to increase the Pinpoint active and inactive polling rates so that the polling does not overload the system. Also, in the CyberStation General Preferences dialog you may want to increase the Time Interval Between Requests setting to slow the graphic polling engine which will also aid in avoiding network overload during graphic polling.
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Don’t: When exporting points to other controllers, do not create export refresh programs setting the point's attribute "Refresh" to true. This creates excessive, unnecessary network traffic.
Note: Refreshing points, for a wireless system, is not required. All traffic is sent as a guaranteed delivery from controller to controller.